Reconstruction and catalytic activity of hybrid Pd(100)/(111) monolayer over γ-Al2O3(100) in CH4, H2O, and O2 dissociation

Rybakov, A.A.; Todorova, S.; Trubnikov, D.N.; Larin, A.V.

Авторы: Rybakov A.A., Todorova S., Trubnikov D.N., Larin A.V.
Журнал: Dalton Transactions
Том: 50
Год издания: 2021
Издательство: Royal Society of Chemistry
Местоположение издательства: United Kingdom
Первая страница: 8863
Последняя страница: 8876
DOI: 10.1039/D1DT01345A
Аннотация: The importance for catalysis of the “heterogeneity” of a Pd monolayer induced by interaction with a semi-ionic support was evaluated. The geometry of Pd monolayer was optimized over the (100) plane of γ-Al2O3 at fixed unit cell parameters defined by the oxide. Simulation of deposition of a whole Pd monolayer in the flat Pd(100) form cut from a bulk led to a formation of a slightly distorted Pd(111) monolayer. The subsequent chemisorption or dissociation of CH4 or H2O at the Pd(111) layer resulted in a new hybrid Pd(100)/(111) structure containing alternate elements of the (100) and (111) planes (the parallel bands of squares and triangles) being similar for both CH4 or H2O reactions and containing two isolated Pd mono-vacancies. The hybrid Pd(100)/(111) layer without chemisorbed species turned out to be more stable than the initial distorted Pd(111) one. The catalytic capabilities of these monolayer structures have been demonstrated for methane dissociation and water gas shift reaction (WGSR) due to lower predicted activation barriers for CH4, H2O, and O2 dissociation at hybrid Pd(100)/(111) layer relative to those at pure (bulk) Pd(100) surface. Moreover, moderate exothermic heats of these reactions were calculated instead of endothermic heats at the Pd(100) or Pd(111) surfaces. The heats of H2O and NH3 adsorption at various monolayers were tested to reveal a dependence on the Pd atomic charges. The relevance of the model of heterogeneous Pd monolayer for explaning the maximum of reaction rate experimentally observed at different Pd coverage is discussed. A transferability of the geometry and the extent of charge inhomogeneity of the hybrid monolayer without vacancies were also tested at the same γ-Al2O3(100) support for Pt, Rh, and Ag.
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Reconstruction and catalytic activity of hybrid Pd(100)/(111) monolayer over γ-Al2O3(100) in CH4, H2O, and O2 dissociationстатья

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